1. Field of the Invention:
This invention relates to chloroacetyl chloride, chloroacetyl chloride in combination with various impurities, and a process for eradicating the impurities from chloroacetyl chloride.
2. Description of the Prior Art:
Larsen et al., U.S. Pat. No. 3,674,664, teach a method of preparing chloroacetyl chloride (CAC) by photochemically oxidizing vinylidene chloride. While this process is industrially attractive, it does produce small (100-250 ppm) amounts of bis-chloromethyl ether (CME), an impurity and a known carcinogen, and 1,1,1,2-tetrachloroethane (TCE), also an impurity but of considerably less toxicity. Since CAC is used as an intermediate in the manufacture of various pesticides and pharmaceuticals, it is desirable to eradicate as much of the CME and TCE from the CAC as possible. Moreover, higher production costs are experienced because CME- and TCE-contaminated CAC prohibits CAC recycle because of CME and TCE accumulation. Consequently, more waste is experienced.
The preferential eradication of CME and TCE from CAC is not amenable to most chemical and physical separation methods. CAC and CME are sufficiently similar in their chemical reactivities and CAC, TCE and CME are sufficiently similar in their physical properties to render conventional separation methods, such as selective absorption, azeotropic or fractional distillation, or complexing, generally ineffective.
Dhingra, "Removal of Bis-Chloromethyl Ether from Chloroacetyl Chloride", Ser. No. 728,103 and filed Sept. 30, 1976 teaches removal of CME from CAC by a process comprising contacting a mixture comprising CAC and CME with hydrochloric acid at a temperature between about 30.degree. C and about 160.degree. C in the presence of a catalytic amount of a Lewis or strong protic acid, such as aluminum chloride or oleum. The Dhingra teaching differs from the present invention in that the presence of hydrochloric acid is critical to the Dhingra process whereas it is noncritical to the present invention.